1. Field of the Invention
The present invention relates to a method for treatment of cataract which comprises administering a 15-ketoprostaglandin compound to a subject.
Prostaglandins (hereinafter, prostaglandins are referred to as PGs) are members of a class of organic carboxylic acid that are contained in human and most other mammalian tissues or organs and that exhibit a wide range of physiological activities. Naturally occurring PGs possess as a common structural feature the prostanoic acid skeleton: ##STR1## Some synthetic analogues have somewhat modified skeletons. The primary PGs are classified based on the structural feature of the five-membered cycle moiety into PGAs, PGBs, PGCs, PGDs, PGEs, PGFs, PGGs, PGHs and PGJs, and also on the presence or absence of unsaturation and oxidation in the chain moiety as:
Subscript 1 -- 13,14-unsaturated-15-OH PA0 Subscript 2 -- 5,6- and 13,14-diunsaturated-15-OH PA0 Subscript 3 -- 5,6- 13,14- and 17,18-triunsaturated-15-OH
Further, PGFs are sub-classified according to the configuration of hydroxy group at position 9 into .alpha.(hydroxy group being in the alpha configuration) and .beta.(hydroxy group being in the beta configuration).
2. Background Information
Naturally occurring PGE.sub.1, PGE.sub.2 and PGE.sub.3 are known to have vasodilating, hypotensive, gastro-juice reducing, intestine-hyperkinetic, uterine contracting, diuretic, bronchodilating and anti-ulcer activities. Also, PGF.sub.1.alpha., PGF.sub.2.alpha. and PGF.sub.3.alpha. are known to have hypertensive, vasocontracting, intestine-hyperkinetic, uterine contacting, luteo-regressive and bronchocontracting activities.
In addition, some 15-keto (i.e. having an oxo group at position 15 in place of the hydroxy group) prostaglandins and 13,14-dihydro-15-keto-prostaglandins are known as substances naturally produced by enzymatic actions during metabolism of primary PGs (Acta Physiologica Scandinavica, 66, 509, 1966). It has also been described that 15-keto-prostaglandin F.sub.2.alpha. has an antipregnant activity.
European patent application no. 0,310,305 describes that 15-keto-PGs can be used as catharitics. However, it has not been reported that 15-keto-prostaglandin compounds have an activity useful in treatment of cataract.
As a result of extensive studies about the biological properties of 15-ketoprostaglandin compounds, the present inventor has discovered that these compounds are useful as an agent for treating cataract.